1. Field of the Invention
The present invention relates to novel organopolysiloxane compositions that are stable in storage in the absence of moisture, but crosslinkable into self-adhesive elastomeric state in the presence of moisture, and, more especially, to such novel organopolysiloxane compositions comprising, as essential constituents, an .alpha.,.omega.-dihydroxydiorganopolysiloxane polymer, a ketiminoxysilane crosslinking agent, an inorganic filler and a curing catalyst.
2. Description of the Prior Art
Single-component organopolysiloxane compositions crosslinkable into elastomeric state have long been known to this art. Compare, for example, French Patents FR-A-1,314,649, FR-A-1,371,250, U.S. Pat. Nos. 3,678,003 and 3,986,999, British Patent GB-A-1,468,467, Belgian Patent BE-A-901,479 and European Patent EP-A-157,580.
These compositions, designated oxime CVE (Cold Vinyl Elastomeric) compositions hereinafter, are particularly useful for coating and jointing applications and especially as a sealing agent in the construction industry for producing glazed structures.
For this particular application, the cured elastomer must not crack, must have a suitable modulus of elasticity and must firmly adhere to glass and to the material constituting the structure in which the glass is mounted, such as wood, aluminum, concrete, PVC (polyvinyl chloride), natural and synthetic rubbers, stone, earthenware and brick.
Such oxime CVE elastomeric compositions, more particularly when they contain pulverulent inorganic fillers of the ground quartz, ground or precipitated calcium carbonate or precipitated silica type, can have an insufficient stability (less than 6 months) in storage in the absence of atmospheric moisture, which is observed as a more or less rapid progressive loss of extrudability, in most cases with a deterioration in the adhesive properties.
This poor storage behavior is not due, as in the case of organopolysiloxane compositions containing an alkoxysilane crosslinking agent, to a poor functionalization of the .alpha.,.omega.-dihydroxy silicone oils by the ketiminoxysilane. In fact, ketiminoxysilanes react completely with the silanol endgroups of these oils at room temperature.
After long and costly research, it has now been determined that the degradation of the oxime CVE compositions in storage appears to be due essentially to the presence of water which is in most cases introduced by the pulverulent fillers.